A. FIELD OF THE INVENTION
This invention is in the field of chemical processes for preparation of iodopropargyl carbamates.
B. DESCRIPTION OF THE PRIOR ART
Polyphase.RTM. fungicide is one of the leading paint mildewcides in the market place currently. The active ingredient is N-butyl iodopropargyl carbamate.
Troy Chemical Corporation U.S. Pat. No. 3,923,870 discloses what is presumed to be the commercial process for preparing N-butyl iodopropargyl carbamate. ICI European Pat. Appl. 0014032 published Jun. 6, 1990 discloses reacting an alkynol with an isocyanate and followed by iodination. The Troy and ICI disclosed processes use butyl isocyanate which is presumably produced from the reaction of butyl amine with phosgene. Isocyanates are generally toxic and are hazardous materials to handle. Troy's more recent process patent, GB 222 0000 published Jun. 23, 1989, discloses a method which uses as a starting material alkynyl chloroformate which is presumably produced from the reaction from propargyl alcohol and phosgene. Alkynyl chloroformate is also toxic, unstable, and hazardous. Although phosgene is a cheap raw material, it is also a very hazardous material. Presumably the cost of production of N-butyl iodopropargyl carbamate is greatly influenced by the procedures necessary for the safe handling of phosgene.
EP patent publication 0539092 A (U.S. Ser. No. 07/782,039) assigned to Rohm and Haas, the same assignee as the present invention, also discloses a process for the preparation of N-butyl iodopropargyl carbamate that avoids the use of phosgene and isocyanates.